PROJECT SUMMARY Urological Chronic Pelvic Pain Syndrome (UCPPS) is a complex and multifactorial disorder characterized by voiding and/or sexual dysfunction, visceral hyperalgesia, and chronic pelvic pain (CPP). Previous animal studies from our laboratory established that peripheral neurogenic inflammation together with central sensitization play a role in generation and maintenance of UCPPS symptoms. Recent study from the MAPP network confirmed that VEGF could be one of the potential urinary biomarkers of UCPPS. Specifically, patients with UCCPS had significantly higher levels of urinary VEGF and VEGF receptors than healthy controls. Additionally, pain severity was significantly associated with increased urinary VEGF suggesting that it may serve as a clinically useful diagnostic marker for UCPPS. Despite this novel clinical data, the sites and mechanisms of VEGF action in the CNS centers controlling micturition, effects on excitability of peripheral and central neurons innervating the lower urinary tract (LUT) are still unknown. Therefore, demonstration of mechanistic involvement of VEGF in bladder pain and voiding dysfunction would provide scientific justification and ?proof-of-concept? data for designing clinical trials of anti-VEGF treatments to alleviate LUTS and bladder pain in UCPPS. While the role of VEGF in angiogenesis has been previously well established, much less is known about its participation in neurogenesis of visceral pain. We were the first group to provide direct evidence that intravesical instillation of VEGF in mice promoted a significant increase in density of both sensory and motor nerves, which was associated with urodynamically recorded detrusor overactivity and enhanced abdominal sensitivity. Current application builds upon our initial findings, and is focused on determining the mechanisms by which VEGF modulates neural plasticity of bladder peripheral and spinal neurons innervating the lower urinary tract. It will also explore potential cross-effects of the VEGF-activated bladder nociceptive (pain-associated) pathways with the micturition reflex, as observed in patients with UCPPS. Additional studies will test pharmacological approaches using available VEGF neutralizing antibodies to evaluate their potential to limit pain sensation and restore bladder function using translational animal models of bladder pain and voiding dysfunction. Overall, the study will result in novel, interpretable data that expands recent MAPP studies in a hypothesis-driven complementary fashion, and will fill the knowledge gap necessary for the development of individualized therapeutic approaches for patients with UCPPS.